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Title: Seasonal changes in streamwater concentration and pathways of phosphorus in a forested catchment under a temperate climate
Authors: Verheyen, Dries ×
Van Gaelen, Nele
Ronchi, Benedicta
Govers, Gerard
Merckx, Roel
Batelaan, Okke
Struyf, Eric
Diels, Jan #
Issue Date: Apr-2014
Publisher: Copernicus GmbH
Host Document: Geophysical Research Abstracts vol:16
Conference: EGU General Assembly edition:11 location:Vienna, Austria date:27 April - 2 May 2014
Article number: 12502
Abstract: In forest ecosystems phosphorus (P) is regarded to be among the most limiting nutrients. Therefore, P is cycled in
an almost closed system, so that losses of P are minimal. Litterfall and leaf decomposition are key processes that
control nutrient dynamics between forest and river systems and can cause losses of P. It is important to understand
the dynamics and seasonal variations of P because P input-output balances can have an effect on sustainability of
forest ecosystems.
A forested headwater catchment (230 ha) has been monitored for different fractions of dissolved (<0.45
m) P concentration in the river and in soil- and groundwater from January 2011 until December 2013. The P
measurements consisted of dissolved reactive P with colorimetry and total dissolved P with ICP-OES. Base flow
samples were taken twice a week and when discharge events occurred, samples were taken flow proportional with
an ISCO sampler. Leaf decomposition was measured in a column test under different fluxes of water to assess P
fluxes out of the decomposition of the litter layer.
The yearly flux of P out of the catchment was on average 0.2 kg P.ha-1.y-1. There was a clear difference
in total P concentration between summer and winter in the river water. In winter, the concentrations were low
(<0.2 mg P/l), even when a rainfall event occurred. In summer, concentrations of total P rose up to 0.6 mg P/l
in the base flow. In the peak flow they lowered due to dilution effects. The rise in P concentration in the base
flow in summer could only be attributed to in-river processes, because no hydrologic pathway of P reaching the
river could explain this particular rise in concentration. Concentrations of P remained low in groundwater (0.035 +- 0.039 mg P/l) and soil water (0.021 +- 0.14 mg P/l) during the 3 years of measurements. A hypothesis is that
the breakdown of leaf litter aided by temperature driven microbial activity can be accounted for this rise and can
deliver up to half of the flux of P out of a forested catchment connected to a river system.
URI: 
Publication status: published
KU Leuven publication type: IMa
Appears in Collections:Division Soil and Water Management
Department of Earth and Environmental Sciences
Division of Geology
Division of Geography & Tourism
× corresponding author
# (joint) last author

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